fix: Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN11-GNUTLS28-6159417
- https://snyk.io/vuln/SNYK-DEBIAN11-GNUTLS28-6159419
- https://snyk.io/vuln/SNYK-DEBIAN11-ZLIB-6008961
- https://snyk.io/vuln/SNYK-DEBIAN11-SYSTEMD-6277510
- https://snyk.io/vuln/SNYK-DEBIAN11-SYSTEMD-6277510

Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.13.0a6-slim-bullseye
+FROM python:3.13.0b2-slim-bullseye
 
 ENV VIRTUAL_ENV=/opt/venv
 RUN python3 -m venv $VIRTUAL_ENV